Polymer-bound cellulose phenylcarbamate derivatives as chiral stationary phases for enantioselective HPLC

Novel chiral stationary phases (CSP) have been prepared by coating the internal surface of monodisperse macroporous poly(2-aminoethyl methacrylate-co-ethylene dimethacrylate) beads with dimethylphenylcarbamate derivatives of regenerated cellulose. The coating was achieved either by simple adsorption or by chemical bonding using a diisocyanate linker. Separation of enantiomers in normal-phase HPLC mode was used to evaluate the enantioselectivity of all CSPs. The influence of the properties of the polymer support such as pore size, pore volume, and content of the amine functionalities, reaction and separation conditions such as weight ratio of modified cellulose selector to polymer beads, amount of diisocyanate crosslinker, and the composition of the mobile phase on chiral discrimination and chromatographic resolution were also systematically investigated. The CSPs prepared by chemical anchoring were more stable and a wider range of solvents including dichloromethane could be used for the separations. Compared to the coated-type CSPs, the chemically bonded stationary phases enabled the enantioseparations of a larger number of racemates and exhibited enantioselectivity fully comparable to their counterparts prepared using porous silica as a support. However, the benefits of tailored macroporous polymer supports demonstrated earlier with brush-type CSPs did not enhance the performance of the chiral stationary phases prepared from cellulose-based selectors.